Does Atlas/Kato GP35 Need Frame Milling to Fit a Decoder?

[Kisatchie]

Install a DCC decoder and mess around with either 3-step or 28-step speed table, kick-start value, and BEMF settings...

Hmm... Kiz has the
messin' around part
down pat...

[rrjim1]

Install a DCC decoder and mess around with either 3-step or 28-step speed table, kick-start value, and BEMF settings.  That is why it is so much easier to speed-match DCC locos than it is DC locos.  It is not painless, but it is possible.  It won't be perfect either, but close enough for smooth operation.

Right, I don't own very many DCC locos only 201. Again, I know how to speed match been doing it as long as Digitrax has been in business. You can kick that High speed motor all you want, it still will not run any where as slow and smooth as the same loco with a scale speed motor. Yes you can get them to run together but not by slowing the high speed motor, all you get is a jerking motion instead of nice smooth movement. I have both Atlas and Kato locos with scale speed motors that will creep nice and smooth from tie to tie in around 3-4 seconds. You can't get that smooth running buy kick starting an old school high speed motor at a very low voltage.

[peteski]

Right, I don't own very many DCC locos only 201. Again, I know how to speed match been doing it as long as Digitrax has been in business. You can kick that High speed motor all you want, it still will not run any where as slow and smooth as the same loco with a scale speed motor. Yes you can get them to run together but not by slowing the high speed motor, all you get is a jerking motion instead of nice smooth movement. I have both Atlas and Kato locos with scale speed motors that will creep nice and smooth from tie to tie in around 3-4 seconds. You can't get that smooth running buy kick starting an old school high speed motor at a very low voltage.

I'm sorry Jim - I was wrong. You're the absolute expert on DCC speed matching and on Atlas motors. I have absolutely no experience in any of this - I was stricly shutting off my mouth here..  You are correct - there is no way to get acceptable speed matching in DCC between the models with old (fast) and new (slow) motors. I don't know what I was thinking.  Having a senior-moment maybe...   SORRY!

[Chris1274]

is it not the case that faster motors will involve larger jumps in speed between speed steps than slower motors? If a motor maxes out at a scale 200 mph, then you have a little over 7 mph per speed step, while a motor that maxes out at 80 mph will involve a little under 3 mph per speed step.

[bman]

Right, I don't own very many DCC locos only 201. Again, I know how to speed match been doing it as long as Digitrax has been in business. You can kick that High speed motor all you want, it still will not run any where as slow and smooth as the same loco with a scale speed motor. Yes you can get them to run together but not by slowing the high speed motor, all you get is a jerking motion instead of nice smooth movement. I have both Atlas and Kato locos with scale speed motors that will creep nice and smooth from tie to tie in around 3-4 seconds. You can't get that smooth running buy kick starting an old school high speed motor at a very low voltage.

I wasn't aware that Kato made a scale speed motor.  Maybe it's a steam locomotive since I do not own a steam locomotive.  My Kato loco's without DCC on board run about the same speeds as my Atlas locos with the high speed motors and no DCC. As far as my DCC equipped locomotives, I must have also done something wrong when speed matching my high speed Atlas locos and my Kato locos to run with my slower Life-Like and slow speed Atlas motors as they run fine and not jerking.  Sure they won't creep at 1 scale mph, but do they really need to do this?

[rrjim1]

I wasn't aware that Kato made a scale speed motor.  Maybe it's a steam locomotive since I do not own a steam locomotive.  My Kato loco's without DCC on board run about the same speeds as my Atlas locos with the high speed motors and no DCC. As far as my DCC equipped locomotives, I must have also done something wrong when speed matching my high speed Atlas locos and my Kato locos to run with my slower Life-Like and slow speed Atlas motors as they run fine and not jerking.  Sure they won't creep at 1 scale mph, but do they really need to do this?

I never said that my Kato locos came with scale speed motors, I replaced most of my Kato locos with Atlas scale speed motors.
I also never said that you couldn't get locos speed matched to run together, what I said was you can't slow a high speed motor down below it's running speed and keep it running smooth. Of course this is just plain common sense.
A real train doesn't start at 10+ MPH, and of course we don't need our models to start at 1 SMPH, but 2-4 SMPH is real nice.
 I have worked on N-scale locos for 45 years and one of my main goals was to get these rockets slowed down. It wasn't happy until Atlas came out with there scale speed motor, a Kato loco with a scale speed Atlas motor runs the way I want them to run. It's one great motor.

[Wolf N Works]

I wish there was a bulk order to get a better price on the motors. I could use a bunch, it has always been on the list to do but this task (remotoring) always gets bumped down LOL.
I do miss the weight of the old frames as compared to the new ones that are DCC, but I am addicted to DCC and sound...

[randgust]

Meanwhile, Vincent, the thread now has a life of its own....

As a DC guy, I've done all kinds of tinkering with matching motor speeds.   For the most part, a good transistor throttle with adjustable input voltage and a square-wave output will 'sync' motors quite nicely if they are anywhere close.    I've tested on straight DC vs. transistor throttles and there's just no comparison.

On straight DC, it's all about how good the rheostat is matched to the resistance in the motor.   I've had to pile on additional heavy resistors in series and in parallel to get the control ranges I've needed, and decided for the most part it's the wrong way to solve the problem.  But I've got a series of switches on my panel that I can keep piling in additional resistors if I need to.  That deals with the slow-speed control but not the motor matching.

I've got quite a mix of 'standard' mechanisms; Kato, Atlas (old and new), Life-Like, Intermountain.   On the transistor throttle, pretty much any locomotives with the same motor will MU just fine.   The trick is trying to get the faster motors (old Atlas) to slow down enough to work with either Kato, or new Atlas.

Resistors won't work, but a bridge of side-by-side diodes pointed in opposite directions will drop motor voltage by about 1.5 volts per pair without creating heat.   I've successfully slowed down fast motors this way for years for matching sets.   You have to put them in series on one side of the motor, and you can pile on as many pairs as you want.  Can be done.

Having said that, I've still worked steadily toward putting similar motors in units that are typically MU'd - I like Kato old mechanisms for six-axles, and have most of the Atlas Classics in one four-axle pool and the slow-speeds in another.   A four-axle typically in a six-axle pool gets a Kato motor.   I certainly like the new mechanisms if for no other reason than for how much quieter they are along with the maximum speed; I've just redone my own set of CF7's to current drives. 

This is a big issue for me as most of my lashups are either three or four units and I'm still a DC guy and while DCC has many advantages, this one is of no particular value to me, I'm just fine.